Washington (Platts): Due to their high cost relative to other generating options, no new nuclear power units will be built in the US, an Exelon official said Thursday.

"The fact is -- and I don't want my message to be misconstrued in this part -- I don't think we're building any more nuclear plants in the United States. I don't think it's ever going to happen," William Von Hoene, senior vice president and chief strategy officer at Exelon, told the US Energy Association's annual meeting in Washington. With 23 operational reactors, Exelon is the US' largest nuclear operator.

"I'm not arguing for the construction of new nuclear plants," Von Hoene said. "They are too expensive to construct, relative to the world in which we now live."

Nuclear power in the US "at this point is really a bridge to a different kind of carbon-free world," he said.

If the existing nuclear units in the US can be kept operational despite the economic challenges they face, and technology can be developed to store energy generated by renewable technologies, which are currently intermittently available, "then we won't need these [new nuclear units] at that point," Von Hoene said. "And we won't build them because they'll be too expensive."

"I think it's very unlikely that absent some extraordinary change in environment or technology, that any nuclear plants beyond the Vogtle plant [in Georgia] will be built in my lifetime, by any company," Von Hoene said in an interview at the meeting Thursday.

The two-unit expansion of Georgia Power's Vogtle nuclear plant has experienced first-of-a-kind design, licensing, procurement and construction delays, leading in part to the bankruptcy of main contractor Westinghouse. Georgia Power says Vogtle-3 and -4 will begin commercial operation in November 2021 and November 2022, respectively.

Von Hoene's stance includes so-called small modular reactors, or SMRs, and advanced designs, he said.

"Right now, the costs on the SMRs, in part because of the size and in part because of the security that's associated with any nuclear plant, are prohibitive," Von Hoene said.

"It's possible that that would evolve over time, and we're involved in looking at that technology," Von Hoene said. "Right now they're prohibitively expensive."

The US Department of Energy defines SMRs as reactors of less than 300 MW that are designed to be built in factories and shipped for installation as demand arises.

NuScale Power submitted its certification application to the Nuclear Regulatory Commission in January 2017 for an SMR design, and the agency accepted the application in March for a full technical review.

NuScale is targeting commercial operation of its first SMR for 2026 at the Idaho National Laboratory. Utah Associated Municipal Power Systems (UAMPS) would own the plant, which would be operated by Energy Northwest. UAMPS has not yet decided whether it will construct the reactor.